Solar Cell I-V Test System User Manual

Ossila Solar Cell I-V Test System User Manual (PDF)

Solar Cell I-V Test System

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1. Overview

The Ossila Solar Cell I-V Test System is a low-cost solution for reliable current-voltage characterisation of solar cells. The system is controlled by specially designed software which can perform multiple I-V measurements, determine key metrics of solar cells, and measure these properties over long periods of time. The automated version of the system enables automatic switching between pixels, making measurements faster and easier.

2. EU Declaration of Conformity (DoC)

We

declare that the DoC is issued under our sole responsibility and belongs to the following product:

Object of Declaration

Solar Cell I-V Test System – Manual (T2002A2/T2002B2/T2002D2/T2002E2/T2002F2/T2002G2), Solar Cell I-V Test System – Automated (T2003A3/T2003B3/T2003C3/T2003E3/T2003F3/T2003G3)

The object of declaration described above is in conformity with the relevant Union harmonisation legislation:

Signed:

Name: Dr James Kingsley

Place: Leiden

Date: 16/11/2021

3. Safety

3.1 Warning

3.2 Use of Equipment

The Ossila Solar Cell I-V Test System is designed to be used as instructed. It is intended for use under the following conditions:

• Indoors in a laboratory environment (pollution degree 2).
• Altitudes up to 2000 m.
• Temperatures of 5°C to 40°C; maximum relative humidity of 80% up to 31°C.

The unit is supplied with a 24 VDC power adapter with a power cord for the country of purchase, in accordance with European Commission regulations and British Standards. Use of any other electrical power cables, adaptors, or transformers is not recommended.

3.3 Hazard Icons

The following symbols can be found at points throughout the rest of the manual. Note and read each warning before attempting any associated operations associated with it:

Table 3.1 Hazard warning labels used in this manual.

Symbol	Associated Hazard
	Electrical shock

3.4 General Hazards

Before installing or operating the Ossila Solar Cell I-V Test System there are several health and safety precautions which must be followed and executed to ensure safe installation and operation.

3.5 Power Cord Safety

Emergency power disconnect options: use the power cord as a disconnecting method and remove from wall. To facilitate disconnect, make sure the power outlet for this cord is readily accessible to the operator.

3.6 Servicing

If servicing is required, please return the unit to Ossila Ltd. The warranty will be invalidated if:

• Modification or service has taken place by anyone other than an Ossila engineer.
• The Unit has been subjected to chemical damage through improper use.
• The Unit has been operated outside the usage parameters stated in the user documentation associated with the Unit.
• The Unit has been rendered inoperable through accident, misuse, contamination, improper maintenance, modification, or other external causes.

3.7 Health and Safety - Servicing

Servicing should only be performed by an Ossila engineer. Any modification or alteration may damage the equipment, cause injury, or death. It will also void your equipment’s warranty.

4. Requirements

Table 4.1 details the power requirements for the Solar Cell I-V Test System, and the minimum computer specifications for the Ossila Solar Cell I-V software.

Table 4.1 Solar Cell I-V Test System requirements.

5. Unpacking

5.1 Packing List

The standard items included with the Ossila Solar Cell I-V Test System are:

• Ossila Solar Cell I-V Test System.
• 24 VDC power adapter.
• USB-B cable.
• USB memory stick pre-loaded with the user manual, USB drivers, quality control data, and software installer.
• Resistor test device.

5.2 Damage Inspection

Examine the components for evidence of shipping damage. If damage has occurred, please contact Ossila directly for further action. The shipping packaging will come with a shock indicator to show if there has been any mishandling of the package during transportation.

6. Specifications

The Solar Cell I-V Test System specifications are shown in Table 6.1.

Table 6.1 Ossila Solar Cell I-V Test System specifications.

7. System Components

The Solar Cell I-V Test System is comprised of 2 items: the Solar Cell I-V Test System (Figure 7.1 or Figure 7.2) and the Ossila I-V Curve software (Figure 7.3).

8. Installation

1. Install the Ossila Solar Cell I-V software on your PC. Run the file ‘Ossila-Solar-Cell-IV-Installer-vX-X-X-X.exe’ on the USB memory stick provided. Follow the on-screen instructions to install the software.
2. Connect the 24 VDC power adaptor to the power socket on the rear of the unit.
3. Connect the unit to your PC using the provided USB-B cable, or an Ethernet cable if preferred.

9. Operation

9.1 Measurement Types

The Solar Cell I-V software can perform 3 different types of measurements. Each measurement type can be selected using the tabs at the top of the window. The available measurements are:

1. Characterisation (Section 9.1.1).
2. Lifetime (Section 9.1.2).
3. Stabilised Current (Section 9.1.3).

Each measurement type requires several settings to be selected before it can be performed. Settings that are shared between all measurements are detailed in Section 9.3. Measurement specific settings are detailed in Sections 9.4, 9.5, and 9.6.

9.1.1 Characterisation

The Characterisation tab performs current-voltage (I-V) measurement and analysis of solar cells. The analysis calculates the following properties:

• Power conversion efficiency (PCE)
• Fill factor (FF)
• Short-circuit current density (Jsc)
• Open-circuit voltage (Voc)
• Shunt resistance (Rsh)
• Series resistance (Rs)
• Maximum power (Pmax)

9.1.2 Lifetime

The Lifetime tab tracks PCE, FF, Jsc, and Voc over time by performing periodic I-V measurements and analysis. Between I-V measurements, the solar cell can be held at short-circuit, open-circuit, or maximum power.

9.1.3 Stabilised Current

The Stabilised Current tab lets you measure the evolution of the photogenerated current at specific voltages.

9.2 Quick Start Guide

1. Start the Ossila Solar Cell I-V software. The window shown in Figure 9.1 will open.
2. Choose a measurement type as described in Section 9.1.
3. Place your sample in the device holder.
4. Place the device holder beneath your solar simulator.
5. Set the appropriate settings in the software (explained in more detail in Sections 9.4 - 9.8).
6. Open the shutter of your solar simulator.
7. Click the ‘Measure’ button. For each pixel, measurements are performed using the chosen measurement settings. This process is repeated until all pixels have been measured.
8. If automatic saving is turned on, the measurement data and settings will then be saved.

9.3 Shared Software Settings

The settings in these sections are shared between all measurement types.

9.3.1 System Settings

(I) System Address

Select the COM port or IP address of the connected unit you intend to use (USB and Ethernet connection respectively). This box will be populated automatically with the addresses of any units connected to the computer.

(II) Voltage Source

Select which SMU channel of the Source Measure Unit the test board is connected to. ‘SMU 1’ will be automatically selected when pixel switching is set to ‘Automated’.

(III) Current Range

Select the range of currents to be used for the measurement. This defines the upper limit and accuracy of current measurements that can be performed by the unit. The values for each range are given in Table 9.1.

Automatic range selection will start on the lowest current range and automatically switch to higher ranges if the current increases above the maximum for a range.

Table 9.1 Maximum current and accuracy for the current ranges of the Ossila Solar Cell I-V Test System.

(IV) Sampling Rate

Select the number of samples to be taken for each data point. A higher number of samples per point will improve the accuracy and precision of the measurement. However, this will increase the time taken for the measurement to be performed.

9.3.2 Device Details

(I) Pixel Switching

Select whether changing the connected pixel is done manually, automatically by the system, or whether to use the external connection on the automated system.

(II) Pixels to Test (Automated Switching)

Select which pixels to measure. The pixel numbers are labelled on the device holder.

(III) Number of Pixels (Automated - External and Manual Switching)

Set the number of individual solar cell pixels in the device being measured.

(IV) Pixel Area

Set the area in cm² of each pixel in the device.

(V) Inverted Device

Set whether the device to be measured is inverted. This option should be on if the anode of your device connects to the ‘cathode’ pins in the device holder.

9.4 Characterisation Settings

9.4.1 Measurement Settings

(I) Start Voltage

Set the voltage in volts at which to start the current-voltage measurement. This can be set between -10 V and +10 V.

(II) End Voltage

Set the voltage in volts at which to end the current-voltage measurement. This can be set between -10 V and +10 V.

(III) Voltage Increment

Set the step size in volts for changing the voltage during current-voltage measurement.

(IV) Voltage Settle Time

Set the time in seconds between applying a voltage and measuring the current. This has a maximum of 10 seconds.

(V) Illumination

Set the illumination intensity (in mW.cm^-2) being used during the measurement.

(VI) Hysteresis I-V

This option performs a reverse current-voltage measurement after the forward current-voltage measurement has completed.

This reverses the set start and end voltages and uses the same voltage increment and settle time as the forward measurement.

(VII) Use Shutter

If set to On, the Shutter connection on the Source Measure Unit and automated system will be activated during a measurement and deactivated afterwards.

When activated, the shutter outputs a constant 5 V signal.

9.5 Lifetime Settings

9.5.1 Measurement Settings

(I) Start Voltage

Set the voltage in volts at which to start the current-voltage measurement. This can be set between -10 V and +10 V.

(II) End Voltage

Set the voltage in volts at which to end the current-voltage measurement. This can be set between -10 V and +10 V.

(III) Voltage Increment

Set the step size in volts for changing the voltage during current-voltage measurement.

(IV) Voltage Settle Time

Set the time in seconds between applying a voltage and measuring the current. This has a maximum of 10 seconds.

(V) Illumination

Set the illumination intensity (in mW.cm^-2) being used during the measurement.

(VI) Hysteresis I-V

This option performs a reverse current-voltage measurement after the forward current-voltage measurement has completed.

This reverses the set start and end voltages and uses the same voltage increment and settle time as the forward measurement.

(VII) Use Shutter

If set to On, the Shutter connection on the Source Measure Unit and automated system will be activated during a measurement and deactivated afterwards.

When activated, the shutter outputs a constant 5 V signal.

9.5.2 Lifetime Parameters

(I) Duration

Set the total duration in hours of the lifetime measurement.

(II) Interval

Set the time interval in minutes between performing repeat current-voltage measurements of the device.

(III) Hold Voltage

Set the voltage that all pixels will be held at between measurements. This can be set as:

• Short-Circuit – hold at 0 V.
• Maximum Power – hold at the average maximum power point determined from most recent current-voltage curve.
• Open-Circuit – hold at the average open-circuit voltage determined from the most recent current-voltage curve.

9.6 Stabilised Current Settings

9.6.1 Measurement Settings

(I) Voltage

Set the voltage to apply to the sample for the measurement. This can be set between -10 V and +10 V.

(II) Total Time

Set the total length of the measurement in minutes.

(III) Measurement Interval

Set the time between each current measurement in seconds.

(VII) Use Shutter

If set to On, the Shutter connection on the Source Measure Unit and automated system will be activated during a measurement and deactivated afterwards.

When activated, the shutter outputs a constant 5 V signal.

9.7 Saving and Loading Settings

(I) Save Settings

Saves the current settings as a profile that can be loaded quickly for use at another time. When clicked, you will be prompted to name the settings profile.

• If the name is already in use, you will be asked if you wish to overwrite the previous profile.
• The name cannot contain the characters: \ / : * ? “ < > |

The settings profile will be added to the drop-down box using the given name.

(II) Settings Profiles

Select a saved settings profile from the drop-down box. The settings fields will be populated with the saved values.

Settings profiles can be deleted by selecting the profile, and then clicking the red ‘delete’ button next to the drop-down box.

9.8 Saving Results

(I) Save After Measurement

Set whether the measurement data will be saved after the measurement has completed.

The program allows for data to be saved automatically and manually once the measurement is complete. For automatic saving, the ‘Saving’ fields must be filled in before the measurement can start, these are detailed below.

For all measurements, a save directory must be specified. This can be done either by:

• Manually typing the directory into the ‘Save Directory’ field.
• Copy and pasting from your file explorer.
• Clicking the file icon button, which will open a dialog box to allow the selection of a folder to save to.

All output files are comma separated variable (.csv) files.

(II) Save Directory

Set the directory in which to create the data files. This can be filled in by:

• Manually typing the directory into the ‘Save Directory’ field.
• Copy and pasting from your file explorer.
• Clicking the ‘Select Directory’ button, which will open a dialog box to allow the selection of a folder to save to.

(III) Device Label

Set the name of the device being tested. This is used to label the files for I-V data and measurement settings.

The field cannot contain the following characters: \ / : * ? “ < > |

(IV) Save Data Format

All data is saved as .csv (comma separated value) files. The figures below show the files that are created when saving data for each of the measurements

9.9 Controls

(I) Measure

Clicking this button will start the measurement using the chosen settings. This button cannot be clicked if the software has not detected the test system.

(II) Abort

Stops a measurement that is currently in progress.

9.10 Plot Controls

(I) Position Readout

Whilst the mouse cursor is over the plot in the Characterisation and Stabilised Current tabs, the x and y position of its location are displayed in the bottom-right of the plot, as shown in Figure 9.16.

(II) Plot Display Controls

By default, the axes of the plot will automatically scale to display all the data within it. The view can be controlled manually using the following mouse controls:

• Left/Middle click and drag – pan the axes.
• Right click and drag – scale the axes (left-right for x-axis, up-down for y-axis).
• Scroll wheel – scale the axes centred on the cursor location.

A specific axis can be controlled by using these controls on the axis labels. The axes can be reset by clicking the ‘A’ button in the bottom-left of the plot, as shown in Figure 9.17.

10. Test Devices

The system is shipped with a test device that can be used to check the calibration of the system. They have resistors arranged in the geometry of the substrate pixels, and the appearance of the test device will depend on the substrate system being used (Figure 10.1).

10.1 Taking a Measurement

1. Plug in and switch on the system.
2. Allow at least 30 minutes for the system to warm up.
3. Place the test device in the device holder with the resistors facing up for S211 and S2006 and facing down for S241/S251.
4. Start the Solar Cell I-V software and enter the following settings in Figure 10.2.
1. These settings can be used with any current range except for the 20 μA range. For this range the start and end voltages must be lowered to -2 V and 2 V respectively.
2. The ‘Pixels to Measure’ checkboxes (Automated systems) or ‘Number of Pixels’ (Manual systems) should match the device configuration you have.

1. Click the ‘Measure’ button.
2. The system should measure straight line resistor responses from -100 μA.cm^-2 to 100 μA.cm^-2 (or -20 μA.cm^-2 to 20 μA.cm^-2 for the 20 μA current range) as shown in Figure 10.3.
3. To check the calibration of the system, use the I-V data to calculate the measured resistance at -10 and 10 V (-2 and 2 V for the 20 μA current range).
1. Resistance can be calculated using: R = V / I
2. For the 200 mA current range the calculated resistance should be between 98 and 102 kΩ (within 2% of the resistor value).
3. For all other ranges the calculated resistance should be between 99 and 101 kΩ (within 1% of the resistor value).

11. Troubleshooting

Most of the issues that may arise will be detailed here. However, if you encounter any issues that aren’t in this list, please contact Ossila.

11.1 Installation and Setup

11.2 Error Messages and Warnings

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